I live in a apartment on 16th floor, I just got a labrador puppy, I am not sure how to potty/pee train him, right now he poops in the balcony and pees on pad, I hope to transition pad to bathroom, and slowly remove the pad entirely. Please suggest is this the right thing to do? Or are there any options?
Short answer: you go outside with your dog so he can go to the toilet. It doesn't matter whether you live on the 16th or 1st floor.
Long answer: I would start training to pee/poo outside as soon as possible. Those pads are great to avoid a mess at home, but they teach the dog that it's ok to pee/poo inside the house.
A puppy doesn't have complete control over his bladder yet, so he must eliminate very often (about every 2 hours). Try to go outside with him for just a few minutes in that interval. And go take a potty break first thing in the morning and last thing in the evening. Go find a nearby tree or patch of grass that will become his toilet. Every time he pees or poops outside, you praise him with your voice, telling him how good he is and so on. Every time he pees or poops at home, you ignore it.
Once he gets older, he'll gain more control over his bladder and you can increase the time between potty breaks.
In addition to all those potty breaks you should take a longer walk once a day. He will probably pee a hundred times during the walk, always just a few drops at a time. This is perfectly normal and is part of dog communication (like writing "I was here" on a wall). You don't need to praise him every time he pees on the walk.
More important is that he understands that the short trip to his toilet tree isn't going to be a longer walk. He should empty his bladder there and not keep any back for later. Therefore you should only go to his toilet tree and back home for a potty break and you should not start his daily walk at the toilet tree, but take a different route.